ABB Substation Condition Monitoring Schedule

 Department:

PSST&DSS

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

NJ

Status:

Date:

Language:

Draft

09/05/25

en

GUIDELINES FOR SUBSTATION SERVICE INSPECTION & CONDITION MONITORING

PSS T & D SUBSTATION – QUALITY MANAGEMENT ABB LTD.

Page 1 of 16 Revision:

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  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

NJ

Status:

Date:

Language:

Draft

09/05/25

en

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1) INTRODUCTION This guideline is prepared in view of the requirements for switchyard service inspection

(visual)

and

condition

based

maintenance

of

substation

equipments, structures and other miscellaneous items in substations. These guidelines are necessarily general. It is recommended to carry out maintenance of equipment as per manual supplied by manufacturer. All inspections and test procedures should also be performed in accordance with applicable codes and standards. The aim of this guideline is to provide in general visual inspection check points for the structures, grounding systems, LT switchboards, etc. for which as such there is no readymade guidelines available. Also to provide the visual inspection and condition based maintenance of Major equipments like Transformer, Circuit breakers, CTs, CVTs, PTs, Disconnectors and LAs etc. to verify the health of the equipments. Service visual inspection is the necessary activity to identify any visible abnormality or failure and require to be performed at specified interval. Whereas condition based monitoring checks (on line/ off line) are necessary to identify internal defects or abnormality, so that necessary preventive action can be taken up.

2) SERVICE INSPECTION & CONDITION MONITORING GUIDELINE The substation in total and the individual items of equipment contained therein should be periodically inspected. Binoculars should be used to view buses and other equipment located on structures.

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

Reviewed:

AG

NJ

Status:

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Painting and Galvanizing (Applicable to all equipments and systems) Depending on geographical location, local environmental condition, periodic inspection of painting and galvanizing condition of structures, panels, equipments etc. is required. Inspect for paint condition, damage paint, chalking effect, rusting etc. If any damage observed, do necessary repaint or repair work. Grounding System Check for loose connections of all ground connections at equipments, structures, panels, other equipments etc. Check for any sparking marks at termination or joint. Observe the condition of any flexible braid type connections for damage. Tighten the connections, clean the joints and replaced if found damage. Earth pits should be kept wet so as to have low resistance. Measure overall ground grid resistance. The Value obtained should be comparable with initially measured values or designed values. Structure Inspect all the structures for loose or missing bolts or nuts. Observe any damage paint/ galvanizing or signs of corrosion. Inspect for deterioration, bending, buckling and cracking. Civil work-Foundation and Control Room Inspect for sings of settlement, cracks, spalling, honeycombing, exposed reinforcing steel, and anchor bolt corrosion. Check for break/ missed cable trench cover. Inspect for any crack/ leakages in control room and water tank. Check for proper functioning of sump pump and drainage system.

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

NJ

Status:

Date:

Language:

Draft

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Buses and Shield wire Inspect for loose clamps or connections. Inspect for bending of Alu-tube bending. Observe the condition of flexible buses and shield wires for any damages. Porcelain Insulators and Bushings (For Bus post / Suspension / Circuit breaker / CT / CVT / PT & Transformer bushings) Inspect all insulators and equipment bushings for chipped petticoats and fractured or cracked porcelain. Flashover in the past may have damaged a portion of the glazing on the porcelain. Make this inspection at close range. Replaced damage bushings. Remove dust and dirt from porcelain insulators with suitable methods. Cable Inspect exposed sections of cable for physical damage. Inspect the insulation or jacket for signs of deterioration. Check for loose connections, lugs, tightness, cracking of lugs etc. Inspect shield grounding (where applicable), cable support and termination. Check for any sparking marks at termination or joint. Clean sparking marks if any and make proper joint with proper tightening and lugging. LT Cable & Metal clad switchgear (Control-Metering, Relay panel, Outdoor and indoor panel) Examine meters, relays and instruments externally to check for loose connections

and

damage

to

cases

and

covers.

Check

whether

the

instruments are reading or registering. Check the functioning of annunciator panels. Inspect for damage to enclosures, doors, latching mechanisms, locks etc. Check out for burned-out lamps.

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

Status:

Date:

Language:

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Battery and battery charger Batteries: Check for any physical damage, loose connections. Check for low level or low specific gravity of the electrolyte. Record the electrolyte temperature. Verify vent cap and flame arresters are in place. Check electrolyte appearance. Check working of exhaust fan. Racks: Check for cleaning and corrosion. Battery charger: Observe temperature (by touch). If temperature is found high, check and attend the reason for the same. Check the charging current and voltage. Observe the ground detector lamps for an indication of an undesirable ground on the dc system. Compressor Check for leakage of air. Check air pressure and Oil level. Substation area- General •

Verify the existence of appropriate danger and informational warning signs. Verify whether they are missing or needs repainting.

•

Check for rusting of fasteners

•

Check

for

any

hotspots

at

conductor/

equipment/

stringing

termination. •

Check for indoor and outdoor lighting systems for burned-out lamps or other component failures

•

Verify that there is adequate supply of spares

•

Inspect the fire protection system

  PSST&DSS Department:

•

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

Reviewed:

AG

NJ

Status:

Date:

Language:

Draft

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Check for bird/ animal nests or other foreign materials in the vicinity of energized equipment, buses or fans.

•

Observe

the

general

condition

of

the

substation

yard,

overall

cleanliness •

Observe the position of all circuit breakers in the auxiliary power system and verify the correctness of this position (indication on breaker).

•

Inspect the area for weed growth, trash and unauthorized equipment storage.

•

Ensure the fence fabric is intact and there is no rust.

•

Ensure the gate latches are operable

•

Ensure flexible braid-type connections are intact. _____ . _____ . _____ . ______. ______

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

Reviewed:

AG

Status:

Date:

Language:

Draft

09/05/25

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NJ

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1. TRANSFORMER A) Service Inspection Schedule Sr.No. 1 2 3 4 5 6 7

Details Checking Checking Checking Checking Checking Checking Checking

of of of of of of of

oil leaks oil level in main tank bushing oil level oil level in conservator oil level in OLTC conservator oil level in oil seal of breather condition of silica gel in breather

Frequency M M M M M M M

B) Maintenance Schedule Sr.No. Details 1 Check manual/ auto actuation of cooler oil pumps and 2 3 4 5 6 7 8

fans Cleaning of all bushings Replacement of damage/ cracked bushings Tightening of loose terminals Maintenance of OLTC driving mechanism Checking and cleaning of diverter contacts Checking and calibration of OTI , WTI Checking of all remote indications (WTI and Tap

9

position indicator) and top up oil in pockets, if required Electrical checking/ testing of pressure relief device,

Frequency Y Y SOS SOS Y 2Y 2Y Y Y

Buchholz relay, OLTC surge relay/ checking of alarm/ 10 11 12 13 14 15 16 17

trip contacts Checking/ replacements of gaskets of terminal box Checking/ testing of Buchholz relay by oil draining Filtration/ degassing of main tank oil Filtration/ replacement of oil of OLTC Testing of bushing CTs Testing of bushing CTs Checking tightness of earthing connections Checking of alignment of horn gap Check for damage paint condition and corrosion for complete transformer with control cabinet

Y Y SOS SOS SOS Y Y Y

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

Status:

Date:

Language:

Draft

09/05/25

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18 *

Marshalling box (i) Cleaning of marshalling boxes of transformer and

Y

* *

OLTC (ii) Tightening of terminations (iii) Checking of contactors, space heaters, illumination

Y Y

19 20

etc. External cleaning of radiators Check tightness of all clamps and connectors

Y Y

C) Condition Monitoring (Condition based Maintenance) Sr.No. 1 2 3 4 5 6 7

Details Dissolved Gas Analysis Oil physical and chemical tests Infrared scan Ultrasonic Partial discharge Sonic Fault detection Vibration Analysis BDV, ppm of OLTC Diverter compartment oil (less

Frequency ½Y ½Y 2Y 2Y 2Y 2Y Y

8 9 10 11

frequently if operations are not more) Frequency Response Analysis C & Tan δ measurement of bushings C & Tan δ measurement of windings IR measurement of windings (Polarization index and

SOS Y 2Y 2Y

12 13 14 15 16 17 18 19

D.A. Ratio) Measurement of winding resistance at all tap positions Measurement of winding ratio Recovery voltage measurement Degree of polymerization Core to Ground resistance Magnetic Balance test Magnetizing current test Furfuradehyde analysis

4Y SOS SOS SOS SOS SOS SOS SOS

2. CIRCUIT BREAKERS (SF6 & AIR BLAST) A) Service Inspection Schedule Sr.No. Details

Frequency

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

NJ

Status:

Date:

Language:

Draft

09/05/25

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1 2 3 4 5

Check for any gas/ air leakage Check for proper gas/ air pressure Check for any hot spots at any terminals Checking of oil leaks from grading capacitors Checking of air compressor for oil level, oil quality, air

M M M M QY

6

filter, V-belt tension Check for crack in insulators

M

B) Maintenance Schedule Sr.No. Details 1 Check tightness of all clamps and connectors / 2 3 4 5 6 7 8 9

terminals Check for damage paint condition and corrosion Replaced damaged bushings Checking of all interlocks Checking of pressure settings Cleaning of breaker interrupter, support insulators, PIRs and grading capacitors Checking of Close/ trip coil currents Checking of healthiness of operation counter Control cabinet (i) Checking of tightness of all cable termination in MB (ii) Checking of door sealing gaskets and replacement,

10 11 12

if necessary (iii) Repainting of metallic surfaces (iv) Checking of space heaters Checking of tightness of foundation bolts Maintenance of air dryers in Air blast circuit breakers Functional checking of auto starting of air compressors

13

and dryers Checking of air pressure drop during duty cycle

14 15

operation Overhauling of compressors Maintenance of air dryer if provided

Frequency Y Y SOS Y Y Y Y Y Y Y SOS Y Y ½Y Y Y SOS ½Y

  PSST&DSS Department:

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GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

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Status:

Date:

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Spring operated mechanism (i) Oil leakages from close and open dashpots, replace

Y

the same if leakage observed (ii) Greasing/ lubrication of gears and various latches

Y

in the operating mechanism (iii) Checking of play of gaps in catch gears (iv) Maintenance of spring charging motors, cleaning

Y Y

17 18

of carbon brushes and contactors (v) Replacement of oil in dashpots Checking of pole discrepancy relay Functional checks, duty cycle operation including rapid

19

re-closing (O-0.3s-CO) Checking of air pressure drop during duty cycle

U

20

operation Checking of all operational lock-outs including SF6

Y

21 22 23

density monitor Checking tightness of earthing connections Cleaning of auxiliary switch contacts with CTC Checking of local ON/OFF indicating lamps in breaker,

Y Y Y

24 25

if provided Check interlocking of isolators with breaker After maintenance trip the breaker through backup

Y Y

SOS Y Y

C) Condition Monitoring (Condition based Maintenance) Sr.No. 1 2 3

Details CB operating timings (Main, PIR, Aux.) Static contact resistance measurement Dynamic contact resistance measurement (DCRM),

Frequency Y 2Y 2Y

contact travel, contact speed, contact wipe, arcing 4

contact length Capacitance and tan δ measurement of grading

4Y

5

capacitors Dew point measurement of SF6 gas

3Y

  PSST&DSS Department:

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GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

Status:

Date:

Language:

Draft

09/05/25

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Dew point measurement of operating air at the outlet

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Y

of air dryer (for Air blast CB) 3. CURRENT TRANSFORMER A) Service Inspection Schedule Sr.No. 1 2 3 4

Details Checking of bellow expansion Checking of oil leakage and crack in insulators etc. CT Marshalling box - Checking of oil leakage in terminal box Check corona effects

Frequency M M M M

B) Maintenance Schedule Sr.No. Details 1 Checking of oil leakage in terminal box 2 Checking of primary connection strips, if provided 3 4 5 6

externally N2 pressure checking Checking of primary connection strips, if provided internally Checking of burden on secondary winding CT Marshalling box - Check healthiness of gaskets - Checking of space heater and illumination - Checking the tightness of all connections including

Frequency Y Y 2Y SOS SOS Y Y Y

7 8

earthing of PF terminal - Cleaning of marshalling box and junction box Checking for rusting and paints Check tightness of all clamps and connectors /

Y Y Y

9

terminals Checking tightness of earthing connections

Y

C) Condition Monitoring (Condition based Maintenance) Sr.No. Details

Frequency

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

Status:

Date:

Language:

Draft

09/05/25

en

NJ

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1 Thermovision scanning of CT Y 2 Measurement of Capacitance and Tan δ 2Y* 3 IR measurement (DAR) 2Y 4 Measurement of CT secondary resistance SOS 5 Magnetization characteristics SOS 6 CT ratio test SOS 7 DGA and testing of other parameters of oil SOS * To be repeated before one year from commissioning and then as per schedule

4. POTENTIAL TRANSFORMERS/ CAPACITANCE VOLTAGE TRANSFORMERS/ COUPLING CAPACITORS A) Service Inspection Schedule Sr.No. 1 2 3 4

Details Checking of bellow expansion Checking of oil leakage and crack in insulators etc. Marshalling box - Checking of oil leakage in terminal box Check corona effects

Frequency M M M M

B) Maintenance Schedule Sr.No. 1 2 3

Details Checking of oil leakage in terminal box Measurement of voltage at control room panel Visual checking of earthing HF point (in case it is not

4 5

being used for PLCC) Checking of any breakage or cracks in cementing joint Cleaning of CVT capacitor stacks and tightness of terminal connections

Frequency Y ½Y Y Y Y

  PSST&DSS Department:

6

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

Status:

Date:

Language:

Draft

09/05/25

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NJ

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Marshalling box - Check healthiness of gaskets - Checking of space heater and illumination - Checking the tightness of all connections including

Y Y Y

7 8

earth connections - Cleaning of marshalling box and junction box Checking for rusting and painting Check tightness of all clamps and connectors /

Y Y Y

9

terminals Checking tightness of earthing connections

Y

C) Condition Monitoring (Condition based Maintenance) Sr.No. Details Frequency 1 Thermovision scanning of Capacitor stacks Y 2 Measurement of Capacitance and Tan δ 3Y* 3 Testing of EMU tank oil for BDV (if oil found discolored) SOS * To be repeated before one year from commissioning and then as per schedule. This test is not possible to be conducted at site if isolation of neutral of intermediate PT is not possible at site. 5. DISCONNECTORS AND EARTH SWITCHES A) Service Inspection Schedule Sr.No. Details 1 Checking of cracks in insulators 2 Observe the condition of contact surfaces and the area 3

around them Inspect the ease of operating mechanism (if possible)

Frequency Y QY QY

B) Maintenance Schedule Sr.No. Details 1 Cleaning and lubrication of main contacts, earthing 2 3

blades, pins and bearings Checking of tightness of bolts, nuts and pins, etc. Cleaning of support insulators and checking of

Frequency Y Y Y

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

Status:

Date:

Language:

Draft

09/05/25

en

NJ

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4 5

insulator cracks, if any Checking of interlocks Checking of earth connections of structure, MOM box

Y Y

6 7

and earth switch Operation check of isolator and earth swithch Checking of alignments of main contacts and earthing

Y 2Y

8

blades Checking and lubrication of linkages including

Y

9 10

transmission gears Checking and tightening of stopper bolts Cleaning of auxiliary switch contacts and greasing with

Y Y

11

silicon grease Lubrication of operating mechanism hinges, lock joints

Y

12 13 14 15 16 17 18

on levers, bearings Checking of all mounting bolts for tightness Checking of healthiness of door gaskets Checking of tightness of electrical connections Checking of spare heaters and illumination Checking of aluminum/ copper flexible connectors Checking for rusting and paints Check corona balls and rings for damage

Y Y Y Y Y Y Y

C) Condition Monitoring (Condition based Maintenance) Sr.No. 1 2 3

Details Thermovision scanning Main contact resistance measurement Earthing contact resistance measurement

Frequency Y 2Y 2Y

6. SURGE ARRESTERS A) Service Inspection Schedule Sr.No. Details 1 Checking of cracks in insulators 2 Check for pitted or blackened exhaust parts or other

Frequency QY QY

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

Status:

Date:

Language:

Draft

09/05/25

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NJ

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evidence of pressure relief B) Maintenance Schedule Sr.No. 1 2 3

Details Testing of counters and leakage current meters Cleaning of insulators Checking of earth connections between surge arrester,

Frequency Y Y Y

surge monitor and earth C) Condition Monitoring (Condition based Maintenance) Sr.No. Details 1 Checking of leakage current (Third harmonic resistive 2 3

current) Measurement of capacitance & Tan δ of each stack Measurement of IR of each stack

Frequency Y SOS SOS

7. WAVE TRAPS A) Service Inspection Schedule Sr.No. Details 1 Check for mechanical integrity of the main coil

Frequency Y

B) Maintenance Schedule Sr.No. 1 2 3 4

Details Tightness and Cleaning of wave trap General inspection / cleaning of tuning unit Cleaning of post insulators (if provided) Repair of bird guard

Frequency Y Y Y SOS

C) Condition Monitoring (Condition based Maintenance) Sr.No. 1 2 3

Details Thermovision scanning of joints HF characteristics of line trap Measurement of blocking impedance and blocking

Frequency Y Y 2Y

  PSST&DSS Department:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORING Prepared:

AG

Reviewed:

NJ

Status:

Date:

Language:

Draft

09/05/25

en

Page 16 of 16 Revision:

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resistance M- Monthly, QY-quarterly, Y-yearly, 2Y-once in 2 years, 3Y-once in three years, 4Y- once in 4 years, SOS-as and when required.

3) CONCLUSION The fundamental goal of inspection, maintenance and condition monitoring of substation is to preserve the function or operation of a system. Specifically, the function that has to be preserved for electric substations is the delivery of safe, reliable electric power to customers

4) BIBLIOGRAPHY 1. Manual on EHV Substation Equipment maintenance 2. EPRI- Inspection and Maintenance Guidelines for Distribution substation 3. Design Guide for Rural substations-USDA